Lex orandi, lex credendi.
The liturgical law is clear that in the Holy Thursday Mass, this optional foot-washing is to be done to twelve viri (males).
There is a theological reason for this...the Holy Thursday Mandatum is connected to the institution of the priesthood. Even if he does not intend it, he is signaling to dissenters that there is some possibility of ordaining women to the priesthood, which is obviously impossible.
This causes confusion and scandal, even if the intention is initially noble.
The other things are less important, but not unimportant. There is a reason Benedict brought back some of those things; he was teaching an important truth: that there cannot be a break between the past and the present. What is once true is always true. There was not, and could not be, a "rupture" in the 1960s that changed the fundamental nature of the Church and her teaching.
“What was once true is always true”
Yes.
But the American Church has done a very poor job of teaching Catholics about the difference between things that the Church teaches because they are everywhere and always true, and the things that the Church proposes because they are the most useful means of spreading the gospel, which things can and do change from time to time.